Blister card type containers are being employed with increasing frequency by the packaging industry because of the manufacturing economy inherent such containers and also due to the fact that these containers lend themselves to various types of sale displays in which the containers are suspended from hooks or the like on a display stand. These containers are particularly adapted for packaging small articles and comprise a thermoformed, clear plastic enclosure portion having one side thereof essentially open and defined by a flat flange surrounding the opening, and a unitary card portion suitably joined to the face of the blister flange. A closure flap formed integral with the card is hingedly attached to the latter by a fold line in the paperstock, and is further defined by perforated score lines in the card. The consumer opens the container by pulling the closure flap away from the card, thereby tearing the score line and allowing the flap to be swung to an open position in order to gain access to the contents within the container.
Since manufacturing economy is a primary consideration in these type of container, it is undesirable to provide separate locking means thereon since the additional material and labor necessary to devise a locking means would add to the manufacturing cost of the container. Most desirably then, a means of locking the closure flap in its closed position once the user has opened the container is formed integral with the card and/or blister. In this respect, locking structure is disclosed in U.S. patent application Ser. No. 17,604, filed Mar. 5, 1979, and owned by the assignee of the present application, in the nature of a pivotable locking edge along one side of the closure flap which may be pivoted into overlapping relationship to one side of the flange of the blister opposite the card in order to lock the closure flap in its closed position. While this known design is suitable for some types of containers, it requires that the user carefully pivot the locking means into the proper attitude during the closing procedure and limits flexibility in the design of the container since the flange of the blister must be disposed immediately adjacent one edge of the closure flap when the latter is in it closed position.
The present invention overcomes the difficiencies in known prior art closures for blister card type containers by providing locking means which is not only quickly and easily manipulated by a user, but also eliminates the need for positioning the flange of the blister in a particular position with respect to the location of the closure flap in the card. According to the present invention, a blister card type container comprising a thermoformed, clear plastic enclosure bonded to one face of a paperstock card which forms a wall of the container includes locking means formed integral with the card for locking a rectangularly shaped closure flap in the card in a closed position once the container is opened to prevent the accidental escape of contents. The locking means includes a first and second spaced apart pair of cut-lines in the card along one edge of the closure flap. One of the cut-lines in each pair thereof extend from one face of the card only partially in the latter and define a locking edge on the closure flap, while another cut-line in each of the pairs thereof extend from the opposite end of the card partially into the latter and define locking flaps on the card. A tear is produced between cut-lines in each of the pairs thereof when a user initially swings the closure flap to its open position. As the closure flap is swung to its closed position, the yieldably flexible locking edges and locking flaps bend slightly to allow the locking edges to be shifted to a position between the locking flaps and the blister whereby to lock the closure flap in its closed position.